Mitchell G A, Robert M F, Hruz P W, Wang S, Fontaine G, Behnke C E, Mende-Mueller L M, Schappert K, Lee C, Gibson K M, Miziorko H M
Section de Génétique Médicale, Hôpital Ste-Justine, Montreal, Quebec, Canada.
J Biol Chem. 1993 Feb 25;268(6):4376-81.
3-Hydroxy-3-methylglutaryl coenzyme A lyase (HL) catalyzes the final step of ketogenesis, an important pathway of mammalian energy metabolism. HL deficiency is an autosomal recessive inborn error in man leading to episodes of hypoglycemia and coma. Using the N-terminal peptide sequence of purified chicken liver HL, we designed degenerate sequence primers and amplified an 89-base pair (bp) chicken liver HL cDNA fragment. Longer cDNA clones for chicken (1384 bp) and human (1575 bp) HL were obtained by library screening. The peptide sequence predicted from the chicken clone contains two peptides from purified chicken HL. Mature human and chicken HL are 298-residue peptides. The sequence of the human clone predicts a 27-residue mitochondrial leader and a 31.6-kDa mature HL peptide. Human fibroblast and liver RNA contain a single 1.7-kilobase HL message. Two Acadian French-Canadian siblings with HL deficiency were homozygous for a 2-base pair deletion within the Ser-69 codon (S69fs(-2)), predicted to result in a truncated nonfunctional HL peptide lacking a complete active site. S69fs(-2) was not present in 12 other HL-deficient patients of 10 other ethnic origins, showing that HL deficiency is genetically heterogeneous.
3-羟基-3-甲基戊二酰辅酶A裂解酶（HL）催化生酮作用的最后一步，这是哺乳动物能量代谢的一条重要途径。HL缺乏症是人类一种常染色体隐性遗传性先天性疾病，可导致低血糖和昏迷发作。利用纯化的鸡肝HL的N端肽序列，我们设计了简并序列引物，并扩增出一个89碱基对（bp）的鸡肝HL cDNA片段。通过文库筛选获得了更长的鸡（1384 bp）和人（1575 bp）HL的cDNA克隆。从鸡克隆预测的肽序列包含来自纯化鸡HL的两个肽段。成熟的人和鸡HL都是298个残基的肽段。人克隆的序列预测有一个27个残基的线粒体前导序列和一个31.6 kDa的成熟HL肽段。人成纤维细胞和肝RNA含有一条单一的1.7千碱基的HL信使RNA。两名患有HL缺乏症的阿卡迪亚法裔加拿大同胞在Ser-69密码子（S69fs(-2)）内有一个2碱基对的缺失，预计会导致一个截短的无功能HL肽段，缺乏完整的活性位点。在其他10个种族的12名其他HL缺乏症患者中未发现S69fs(-2)，表明HL缺乏症在遗传上是异质性的。
